Volume Unit meter (VU meter) is an application used to monitor the intensity of sound using ALSA programming interface for linux. There are two variants of this application:

1. Using dB (decibels)
2. Using FFT (Fast Fourier Transform)

• 1) Using dB
• 2) Hardware Requirements
• 3) Package Dependencies
• 4) Building and running
• 5) Conclusion

Here, the intensity of sound is calculated by computing RMS value of sampled audio signal and converting to dB. The implementation is straight forward and simple.

Link to blog: http://www.96boards.org/blog/96boards-vu-meter-part-1/

1. HiKey development board
2. USB mic

1. ALSA library

$ sudo apt-get install libasound2

$ git clone https://github.com/96boards-projects/vu_meter.git
$ cd projects
$ cd vu_meter
$ make
$ ./vu_meter plughw:U0x46d0x825

Replace the Sound card info according to your device

Running the executable causes progress bar to move according to the sound intensity.

Under development